Poly Filter and activated carbon

[kkutac001]

Heya, all. Had some questions on these two items:
1. If you use Poly Filter, do you do away with any need for carbon? Or does carbon absorb some things Poly Filter misses?
2. Or, even if PF replaces carbon, do you put carbon in front of the Poly Filter in the water flow, in order to make the Poly Filter last longer?

I like the Poly Filter because there is never any initial 'black dust' (happens even though I pre-rinsed the carbon), and because it changes color as it becomes exhausted. Also, it seems to catch a lot of stuff (like P04, which I don't believe carbon has any affinity for). Having said that, Poly Filter is not cheap. Thus, my questions.

Thanks for any comments, Karl

[GaryP]

Karl,

I guess my answer to your question is, It Depends. Poly filters are probably OK for a small system, but cost prohibitive for a large system. Do they do the same or similar things as carbon? Yes. Carbon does remove organic phosphates but some studies indicate that inorganic phosphate may leach back out when it undergoes bacterial decay. Does the same thing happen with Poly Filters? If it did, do they think they would tell you? Probably not though. Its probably impregnated with some sort of phosphate absorber like Phosguard.

I would say that if you are getting good results with the pads, stay with them. If not, then upgrade to using carbon and a phosphate absorber. I mix the two in my media filter. Another thing, if carbon dust is a concern, try using a granular carbon. While the amorphous carbons (like Black Diamond and Hydrocarbon) are supposedly more effective then the granular, the granular are a lot less dusty. I've been using the Tri Carbon granulated product from CB Pets.

[kkutac001]

Gary, thanks for taking the time to reply. I did not know Carb would remove organic phosphates. Sounds like you might advocate active carb + phos absorber, for the economics of it. Always great when you 'hold forth' on a topic. :-) ..Karl

[tony]

karl, how is the tank coming?

i echo what gary said. i use black diamond and have never had any noticeable dust. when using both ive always put the poly in front of the carbon when i could. not sure if its the best way but it worked for me

[GaryP]

Carbon will absorb most medium to large organic molecules. When they break downb to the small size is when they leach back out of the carbon.

Basically think of carbon as sponge with millions of tiny blind canyons in it. Anything organic that is much larger then a water molecule will get caught in there. There are also millions of bacteria in those canyons that are digesting the organics caught there and chewing them up into smaller sized fragments. While the phosphates are a prized food source for the bacteria, occasionally a fragment pops loose and leaches back out.